148 



with it, gutta percha and cork were hopelessly out of court. He had him- 

 self used paraffin or wax. It was certainly a great advantage to have it 

 black, as attempts to blacken paraffin generally resulted in getting some por- 

 tions of the surface well coated, but others not covered at all. Then again 

 as to pins ; he thought a great deal of the fact that pins would stick into it 

 so well j with paraffin the sides of the hole did not seem to close upon 

 the pin as they ought to do, and so a very slight tension disturbed it, and by- 

 and-by the pin became loose, and then the dissection became disturbed. 

 With this new wax it was not so, there was a sort of elasticity about it 

 which caused it to shut upon the pin and enabled it to bear the strain. He 

 should also be glad to know where these convenient little saucers, shown by 

 Mr. Stewart, were to be obtained ? 



Mr. Stewart said they were to be found at the corners of the streets, 

 containing three whelks or three mussels for a penny. He bought those he 

 had brought to the meeting at a shop in the New Cut, where they were 

 supplied to costermongers. 



Dr. Matthews said he had used heel-ball, such as was used for taking 

 rubbings of bi'asses with ; when this was melted it answered very well. 



Mr. Stewart rather fancied that there was rosin in the heel-ball, and if so, 

 they could not use it in contact with spirit. 



Mr. Thos. Spencer said that such was the case. 



Dr. Matthews said he mentioned it because in case of failure to get the 

 ozokerit, the heel-ball would be found a good substitute, though, of course, 

 it would only do for use with water. 



Mr. T. C White enquired whether a supply of this substance could be got 

 by members of the Club, and at what cost? 



Mr. Stewart said he thought it was worth about lOd. or Is. a pound; he 

 had not the slightest doubt bat that it could readily be obtained if required, 

 especially as Mr. Field was himself a scientific man. " Black wax " was the 

 name they called it at the works. It was soluble to some extent in benzine 

 or turpentine. 



Mr. Hailes said it was a substance very well known now in commerce. It 

 was a kind of native or mineral wax, and was found in Bohemia in large 

 quantities, and now that it could be bleached it was used very largely for 

 making candles. It was found in lumps, and was melted and run into casks 

 for exportation. 



Mr. Thos. Spencer thought that if the material itself was subjected to 

 a bleaching process, possibly this black stuff might be some kind of 

 residuum. 



Mr. Pearson believed that there were some specimens of it, in its native 

 condition, at the Geological Museum in Jermyn Street, and if he remem- 

 bered rightly, they were of a very dark brown colour. 



Mr. lngpen had very little doubt that since the value of this substance 

 for microscopical purposes had been so prominently pointed out, the 

 opticians would soon be able to supply it to those who wanted any. As 

 regarded the best methods of illumination, condensers were by no means so 

 good as reflectors, especially by daylight, when the concave mirror belonging 



